The present disclosure generally relates to a lighting or illumination assembly. More particularly, the present disclosure relates to a lighting or illumination assembly that uses an array of light emitting diodes (LEDs).
Illumination assemblies are used in a variety of diverse applications. Traditional illumination assemblies have used lighting sources such as incandescent or fluorescent lights, for example. More recently, other types of light emitting elements, and light emitting diodes (LEDs) in particular, have been used in illumination assemblies. LEDs have the advantages of small size, long life, and low power consumption. These advantages of LEDs make them useful in many diverse applications.
For many lighting applications, it is desirable to have one or more LEDs supply the required light intensity and/or distribution. For example, several LEDs can be assembled in an array having small dimensions to provide a high illuminance in a small area, or the LEDs can be distributed over a larger area to provide a broader and more uniform illuminance.
LEDs in an array are commonly connected to each other and to other electrical systems by mounting the LEDs onto a printed circuit board substrate. LEDs may be populated onto a substrate using techniques that are common to other areas of electronics manufacturing, e.g., locating components onto circuit board traces, followed by bonding the components to the substrate using one of a number of known technologies, including wave soldering, reflow soldering, and attachment using conductive adhesives.
Common LED packages used to hold LED die include one or more LEDS mounted in a ceramic or plastic package, with electrical connections provided through wires or solder bonds such as surface mounted packages or T-1 3/4-type “jellybean” packages, etc. However, these techniques and designs sometimes provide poor thermal conductivity from the LED package to a heat sink, and the circuitized substrates used can be expensive and sometimes provide poor light reflectivity.
High thermal conductivity can be important for increasing the light output of an LED and extending its operating lifetime. Further, the reflectivity of the substrate can also be important in applications where the LED illuminates an optical cavity and a significant fraction of the light emitted by the LED reflects off the circuit substrate inside the optical cavity.